Merge changes I2731ef15,Ib4b03035

* changes:
  Add a timestamp touch rule.
  Remove the implicit "_" in subnames.
diff --git a/android/androidmk.go b/android/androidmk.go
index 8d2951d..7d7707f 100644
--- a/android/androidmk.go
+++ b/android/androidmk.go
@@ -146,7 +146,7 @@
 	}
 
 	if data.SubName != "" {
-		name += "_" + data.SubName
+		name += data.SubName
 	}
 
 	if data.Custom != nil {
diff --git a/android/defs.go b/android/defs.go
index be28e8b..9c6527d 100644
--- a/android/defs.go
+++ b/android/defs.go
@@ -52,6 +52,13 @@
 		},
 		"cpFlags")
 
+	// A timestamp touch rule.
+	Touch = pctx.StaticRule("Touch",
+		blueprint.RuleParams{
+			Command:     "touch $out",
+			Description: "touch $out",
+		})
+
 	// A symlink rule.
 	Symlink = pctx.StaticRule("Symlink",
 		blueprint.RuleParams{
diff --git a/cc/androidmk.go b/cc/androidmk.go
index 7f18155..70e1f47 100644
--- a/cc/androidmk.go
+++ b/cc/androidmk.go
@@ -134,7 +134,7 @@
 func (test *testBinaryLinker) AndroidMk(ctx AndroidMkContext, ret *android.AndroidMkData) {
 	test.binaryLinker.AndroidMk(ctx, ret)
 	if Bool(test.testLinker.Properties.Test_per_src) {
-		ret.SubName = test.binaryLinker.Properties.Stem
+		ret.SubName = "_" + test.binaryLinker.Properties.Stem
 	}
 }